Inter-cell interference (ICI) may be considered to be interference at a cell due to transmissions originating in another cell. Usually, ICI occurs between adjacent cells of a communications system. As an example, relatively high-powered transmissions to and from a cell edge user (CEU) operating in a first cell may cause more interference to adjacent cells utilizing the same operating frequency than relatively lower-powered transmissions to and from a cell center user (CCU) operating in the first cell to adjacent cells utilizing the same operating frequency due to correspondingly higher power levels of the transmissions to and from the CEU.
FIG. 1 illustrates a prior art communications system 100. Communications system 100 includes a first enhanced NodeB (eNB) 105 and a second eNB 115. An eNB (also commonly referred to as a base station, communications controller, a transmit point (TP), and so forth) usually have a hardware processor that is configured to control communications of User Equipment (UE) operating within its coverage area. For example, eNB 105 may have a coverage area illustrated in FIG. 1 as hexagon 110, while eNB 115 may have a coverage area illustrated as hexagon 120. Operating within hexagon 110 may be a first UE 125 and a second UE 130. The first and second UEs 125 and 130 may be cell phones, smart phones, tablets, or any electronic device having a hardware processor and hardware antennas capable of wireless communication with the corresponding eNB.
A coverage area of an eNB may be categorized based upon a distance to the eNB. For example, coverage area of eNB 105 (i.e., hexagon 110) may be categorized into two regions, with a first region being a cell center region (shown as circle 135) and a cell edge region (portions of hexagon 110 outside of circle 135, shown as region 140). Normally, UEs operating within the cell center region 135, such as UE 125, may receive transmissions made at a lower power level than UEs operating within the cell edge region 140, such as UE 130, due to their closer proximity to an eNB serving the coverage area.
Furthermore, since transmissions made by UEs (i.e., uplink transmissions) operating with a cell edge region, such as UE 130, are usually made at higher power levels and the UEs are also located closer to neighboring (e.g., adjacent) eNBs, the transmissions may cause more interference to the neighboring eNBs. For downlink transmissions, UEs in a first eNB (e.g., a serving eNB) that are located closer to a neighboring eNB (i.e., an adjacent eNB) may experience high interference from transmissions of the neighboring eNB than UEs operating in a cell center region of the first eNB.
ICIC is a simple and efficient ICI management scheme that attempts to reduce and/or control ICI through the use of radio resource management (RRM) methods. Typically, ICIC takes into account information from multiple cells to control ICI. ICIC in Orthogonal Frequency Division Multiple Access (OFDMA) communications systems, such as Third Generation Partnership Project (3GPP) Long Term Evolution (LTE) compliant communications system, have received considerable study in recent years.
ICIC schemes can improve cell edge user performance, especially in scenarios where the interference is dominant in the network. This is accomplished by inter-cell coordinated resource and power allocation. High power frequency band (also commonly referred to as color) assignment helps a cell to improve its UE coverage, especially for cells with high-CEU loadings.